1. Field of the Invention
This invention relates to disassembling apparatus for sectionalized tower crane booms. More particularly, it is concerned with a disassembling apparatus that may be connected to a tower crane boom for dismantling of the boom while the boom is maintained at an elevated position.
2. Description of the Prior Art
Buildings and related structures are commonly constructed with the use of modular tower cranes. It is common to construct the structure around the mast of the crane so that building materials lifted by the boom of the crane may be readily delivered to any point of the structure being constructed. The centering of a tower crane within the structure being constructed, however, makes it impossible to lower the boom of the crane to ground level for dismantling of the boom once the structure is completed.
Heretofore, disassembly of modularized boom sections of tower cranes has been accomplished with the use of helicopters, or through the use of disassembling equipment that is hoisted to the boom and supported by an inboard section of the boom while the outermost section of the boom is lifted by the disassembling equipment. Disassembly of a boom through the use of helicopters is costly and dangerous, and must be accomplished by a skilled crew that can hook cables extending from the helicopter to a boom section while the helicopter hovers over the boom. Connection of the helicopter cables to the boom section, and the disconnecting of the outermost boom section from the inboard sections of the boom must be accomplished during a limited time interval, since the excessive fuel consumption of a helicopter while hovering precludes hovering of the helicopter for extended periods.
Conventional disassembling equipment designed to be supported by inboard boom sections for lifting the outermost boom section of a tower crane has required the use of counterweights to balance the weight of the outermost boom section once it is detached from the inboard boom sections. The operator of the disassembling equipment must correctly determine the weight of the boom section to be detached, and must select a counterweight of a corresponding weight. Moreover, conventional disassembling equipment has not included means for rotating the outermost boom section about its longitudinal axis, to make it possible to relieve sheer stresses across the pin connecting adjacent boom sections. The above described deficiencies have in the past resulted in dismantled boom sections pivoting uncontrollably about disassembling equipment due to the misplacement or wrong selection of counterweights, and in the need for applying excessive force to remove the pin connecting adjacent boom sections.
A disassembling apparatus for sectionalized tower crane boom sections that would stably support a disconnected boom section without the need for counterweights, and which would rotate the outermost boom section of a tower crane about its longitudinal axis to facilitate the removal of pins connecting adjacent boom sections would be a decided advantage.